This collaborative project started with examining the cerebellums role in motor learning. Cerebellum's involvement in the control of different aspects of voluntary movement has been established by the results of lesion, stimulation and single cell recording studies. The interpretation of lesion studies is complicated by the fact that any motor deficits reflect both the absence of the lesioned areas and any reorganization that has occurred elsewhere. Stimulation studies are limited in terms of their non-physiological mode of activation. Single cell recordings have provided a more detailed picture of cerebellar activation in relation to movement planning and execution. However, single cell recordings are limited to the locus of recording with mapping being particularly difficult in the convoluted folia of the cerebellum. Using 4 Tesla functional imaging, we have started a systematic study of the activation in the cerebellum in motor function and motor learning. In the previous annual report, we reported that we addressed the question of whether the degree of cerebellar activity is modulated with skill acquisition and learning during motor tasks that exhibit varying degrees of difficulty in error detection and correction. The data collected suggested that the human cerebellum is most active in situations that require intense attention and error detection-correction (e.g. random task). The cerebellum is also more active during initial stages of learning a new task, but this activity tends to diminish as skill and facility improve the proficiency of the performance. Subsequent to these studies, we investigated whether motor cortical areas (primary motor cortex (M1), the supplementary motor area (SMA), and the premotor area (PM)) also exhibit similar changes in activity during a motor-learning paradigm. The subjects performed the same set of experiments as the cerebellum studies. As learning progressed and performance improved with the learning task, on average, the area of activation in M1, SMA and PM increased. There were no changes in fractional signal intensity change. DS/S of M1 and PM, producing a net increase in activity in these. In SMA, on the other hand, the increase in area was associated with a decrease in DS/S. Subcortically, the caudate nucleus showed no change in the area of activity, but a decrease in DS/S. The lentiform nucleus had an increase in the area of activation and no change in DS/S. These preliminary findings demonstrate that the cerebrum does not display the decrease in activity associated with improved performance during a motor-learning task previously observed in the cerebellum. This observation further supports the conclusion that the changes in activation previously measured in the cerebellum are not due to global hemodynamic alterations but reflect a learning-specific reduction in activity following the acquisition of motor skill at a new task. The increased activation we observed in M1 and PM suggest that activity in these areas may, at least in part, be related to the performance. Typically, with acquisition of skill, increased number of movements can be performed in a given time period, particularly when the constraint of the task is accuracy as it was in this paradigm. In the basal ganglia, the activity of the lentiform nucleus may also reflect this aspect of the performance. The reciprocal connections between these nuclei and motor cortical areas provide ample opportunity for performance-related information to be exchanged and processed.